 |
. |
| If
the nurse is required to mix powdered medications, one should look
at the literature or ask pharmacy if there are special instructions
for the admixture. Many medications that are prepared as powdered
and the nurse must add a given volume of diluent requires a specific
amount in order to calculate and administer a safe dosage.
Arbitrarily adding 10 ml of diluent to a 1 gram medication vial
and making the assumption that you have 100 mg /ml may be erroneous.
Example:
John
has an order for Penicillin G 800,000 Units IVPB q4°.
The nurse has a one million units vial that has the following
information on the vial: Add 9.6 ml of sterile water to
the vial to yield 100,000 U/ml. How many ml will the nurse
withdraw from the reconstituted vial?
What is the critical information?
- The
dosage (800,000 units).
- The
end concentration (100,000 U / ml).
What is extraneous information
not needed for calculating?
- Mixing
instructions (Adding the 9.6 ml to the vial tells you that this
is the volume necessary to add to the powder to yield a specific
concentration.) Can you figure how much volume the powder
has ? (answer
is 0.4 ml [10 - 9.6 = 0.4])
- q
4° (Since you are calculating a single dose, this
information is not necessary to calculate.
100,000
Units
1 ml
|
=
|
800,000
Units
X ml
|
|
100,000
x
|
=
|
800,000
|
|
X
|
=
|
8
ml
|
|
.. |
